# RV Generator Repair, Service and Installation > RV generator repair covers scheduled service, fault diagnosis, overhaul and new installation on Onan, Cummins and comparable units. Work runs $400 to $8,500 across 2 to 35 hours. Most failures trace to disuse rather than wear: fuel varnish, stale filters and brush wear on units that sat between seasons. Source: https://ocrv.biz/services/generator-repair/ Business: OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887. (949) 799-3387. Serving Tustin, California. Ballpark range: $400 to $8,500. Posted rates at https://ocrv.biz/prices/ ## Why do RV generators fail from sitting rather than running? Because everything inside them is designed to be wet with fuel, wet with oil and warm. A generator that runs monthly under load stays that way. One that sits nine months goes through a specific sequence of decay. Gasoline units suffer first and worst. Modern pump gasoline separates and oxidizes within months, and the light fractions evaporate out of the carburetor bowl leaving behind a varnish that plugs the main jet and the idle circuit. The unit cranks, fires briefly on what is left in the intake, and dies. Ethanol content makes it worse by attracting water, which corrodes the bowl and the jet passages. Diesel units decay differently. Fuel grows microbial contamination in the presence of water, which plugs filters. Injectors that sit without cycling can stick. Air enters the fuel system as seals dry, and a diesel that has ingested air will crank without starting until it is bled. Both suffer on the generator end. Brushes and slip rings develop an oxide film when idle, so the unit produces no output on the first start even though the engine runs fine. Bearings develop flat spots in their grease. Rubber mounts take a set. The single most useful thing an owner can do is run the unit under real load for a couple of hours every month. Not at no load, which glazes cylinders on gasoline units and wet stacks diesel units. Under load, with the air conditioners on. ## What does a proper generator service include? Oil and filter, air filter, fuel filter, spark plugs on gasoline units, and inspection of the parts that fail quietly. Oil first, because generator oil works harder than most owners assume. The engine runs at constant speed under varying load with a small sump and limited airflow, so oil degrades on hours rather than on miles. The service interval in the unit manual is in hours and it should be followed on hours. Then the parts that get skipped. The spark arrestor screen in the exhaust clogs with carbon and chokes the unit. The cooling air inlet and the fins pack with dust and debris, and a generator that cannot cool itself derates and eventually shuts down on high temperature. The slip rings and brushes get inspected for wear and for the oxide film. The exhaust system gets checked for leaks, which on a coach is a carbon monoxide question rather than a noise question. Then the load test. This is the step that separates a real service from an oil change. A generator that starts and runs at no load can still fail to carry its rated output, and the failure shows up on the first hot afternoon with two air conditioners running. Load testing in shop puts a controlled load on the unit and measures voltage and frequency stability under it. [Generator maintenance](/services/generator-repair/generator-maintenance/) and repair share the $400 to $8,500 band across 2 to 35 hours, posted on the [price sheet](/prices/). Mechanical labor is $260 per hour and diagnostics are $285 per hour with a one hour minimum applied as a credit against an authorized repair. ## When is an overhaul worth it versus a replacement? It comes down to hours on the unit, the condition of the generator end, and whether the model is still supported with parts. An overhaul makes sense when the engine is worn but the generator end, the control board and the wiring harness are sound, and when parts are readily available. Onan units in particular have excellent parts support across a long production history, which keeps overhaul viable on machines that would be uneconomic in another brand. Replacement makes sense when the generator end has failed, when the control board is obsolete, when the unit is undersized for what the coach now draws, or when the labor to reach a buried installation exceeds the value of the repair. That last one is real: some coaches bury the generator in a compartment that requires removing a slide tray, an exhaust system and a fuel line to extract, and that access labor is the same whether the unit is being repaired or replaced. Sizing matters on replacement. A coach that has added a residential refrigerator, a second air conditioner or an induction cooktop draws more than it did originally. Fitting the same size unit that was there before can leave the owner with a generator that trips on load. [Generator installation](/services/generator-repair/generator-installation/) includes sizing against the actual connected load, the transfer switch, the fuel connection, the exhaust routing and the mounting. ## What connects the generator to the rest of the coach? Four things, and each one is a common source of complaints that get blamed on the generator. The transfer switch decides whether the coach runs on shore or generator power. Its contacts arc every switch cycle and eventually pit, weld or fail open. A generator that runs perfectly but produces nothing inside the coach is usually a transfer switch, and that diagnosis runs $285 to $1,500 under [electrical repair](/services/electrical-repair/). The fuel supply on a gasoline coach draws from the chassis tank through a pickup tube set higher than the main pickup, so the generator runs out of fuel with roughly a quarter tank remaining. That is by design, and owners who report a generator that quits on a long trip are frequently describing this rather than a fault. The exhaust system routes combustion gases away from the coach, and its integrity is a safety item. Leaks in a generator exhaust under a coach can put carbon monoxide into the living space, particularly with a following wind at a campsite. The slide tray, on units mounted on a pull-out tray, has to run smoothly and lock securely. Trays corrode, rollers seize and the tray becomes the reason the unit cannot be serviced. Sibling lines under [mechanical and systems services](/services/mechanical-systems/) are electrical, [plumbing](/services/plumbing-repair/) and [appliance repair](/services/appliance-repair/), and generator faults regularly present as complaints in all three. ## How this job runs 1. **Symptom capture and start test**: The reported behavior is reproduced from cold. Crank, fire, run and output are each observed separately, because a no start, a no output and a fails under load are three different faults with three different repair paths. 2. **Fuel, air and ignition inspection**: Fuel condition and filter state, air inlet and cooling fin condition, spark arrestor, and spark plugs on gasoline units. Most no start conditions on stored units resolve in this stage. 3. **Generator end and control check**: Brushes, slip rings, output voltage and frequency, control board behavior and the wiring between the unit and the transfer switch are all verified before any major component is condemned. 4. **Load test before release**: The unit is run under controlled load and voltage and frequency stability are measured. A generator that has not been load tested has not been proven, regardless of how well it idles in the bay. ## Questions ### My generator starts but the outlets in the coach are dead. What is wrong? Most often the transfer switch, which chooses between shore and generator power and whose contacts burn over time. It can also be a tripped generator circuit breaker on the unit itself. Both are quick to isolate once a meter is on the output side. ### How often should I run my RV generator? Monthly, under real load, for a couple of hours. Running at no load glazes cylinders on gasoline units and wet stacks diesel units, so put the air conditioners on. Units that sit unused between seasons are the ones that arrive here with varnished carburetors and plugged filters. ### Can you install a generator in a coach that never had one? In many cases, yes. It depends on whether there is a compartment or frame space that can carry the unit, how the fuel supply can be tapped, where the exhaust can safely exit and whether the electrical system can accept the transfer switch. That feasibility assessment happens before any quote. ### Why does my generator quit with fuel still in the tank? Gasoline coaches use a generator fuel pickup set higher in the chassis tank than the engine pickup, so the generator runs dry at roughly a quarter tank. That protects the owner from stranding the vehicle, and it is designed behavior rather than a fault. ## Related - [Mechanical and Systems Services](https://ocrv.biz/services/mechanical-systems/) - [Electrical Repair](https://ocrv.biz/services/electrical-repair/) - [Plumbing Repair](https://ocrv.biz/services/plumbing-repair/) - [Appliance Repair](https://ocrv.biz/services/appliance-repair/) - [Generator Maintenance](https://ocrv.biz/services/generator-repair/generator-maintenance/) - [Generator Repair and Overhaul](https://ocrv.biz/services/generator-repair/generator-repair-overhaul/) - [Generator Installation](https://ocrv.biz/services/generator-repair/generator-installation/) - [Prices and Posted Rates](https://ocrv.biz/prices/)